There has been some buzz on the forums recently about small sensor technologies.

1) There is the Nokia 808 with 41 MP sensor producing astonishingly good images2) New Panasonic sensor using a diffraction grid for color separation

Are these and other technologies the death knell of large sensor technologies? In my view, no, yes and even may be.

It is possible to optimize a system. The Nokia has a reasonably large sensor for a phone cam combined with a prime lens from Zeiss optimized for that sensor. It is possible to achieve very good performance with such a combination. The real limitation is that a small sensor does not collect that many photons, which results in more shot noise compared with larger sensors and also reduced DR.

If we look at the panasonic sensor, we have not seen real world results, but the main benefit is probably that it uses all photons available as it doesn't need to loose photons due to filtration. That helps ISO sensivity, but little else.

Now, we have a few different sizes of sensors:

4/3 is pretty good and has a lot of good lenses optimized for the sensor size. 4/3 makes a lot of inroads in old DSLR territory.

APS-C is mature. DSLR lenses are not really optimized for the sensor size, as I see it. There are several mirror less designs, with Fujifilm actually making excellent lenses optimized for the format. Hard to know where the format goes.

Full frame DSLRs have the advantage of size over APS-C, 4/3 and phone cam sensors. Small sensor technology seems to migrate to full frame.

In my view, and limited experience based on APS-C and DSLR I have used, the smaller sensor can deliver, but a larger sensor will always have some advantages. The way I see it a larger sensor collects more photons resulting in smoother highlight and midtones. The larger sensors also make less demand on the lens. It probably takes careful shooting from tripod to fully realize large sensor advantages.

To sum it up: Very good results are possible with really small sensors in optimized systems. To me it seems that smaller formats can be really competitive with larger formats when the smaller format is utilized to it's advantage.

If we go back to film days, medium format was better than 135. At least that was the case in my experience, as long as I shot MF on tripod and didn't need very long depth of field and was shooting with low ISO film.. The Pentax 67 I had needed something like stopping down two extra stops to give the same DoF as my 135 camera. With tripod it was less a problem. What I essentially did was to use 67 with tripod and slow film for careful work and the 135 SLR for handheld shooting, using slow films in both.

The way I see it a larger sensor collects more photons resulting in smoother highlight and midtones. The larger sensors also make less demand on the lens. It probably takes careful shooting from tripod to fully realize large sensor advantages.

I've never understood this. We talk of "crop" sensors and if you take two images, one with a "crop" camera and the other with a "FF" camera and you then crop the FF image to give the same FoV as the crop image wont you get two images that look the same?

There will be differences as the chips will no doubt be slightly different but if we could get both FF and crop cameras with exactly the same chip technology I think they'd look the same. These days many of us have FF and crop cameras that can take the same lens and can try this little experiment and personally I have done it and the results look very largely the same to me. Near as makes no odds anyway. Yes the lenses work less hard on FF due to less magnification but keep image sizes reasonable and it may not matter.

Anyway, I digress... For me the smaller sensor cameras are good enough except when pushing ISO or print size to the absolute limits but I think that FF will live on.

If we go back to film days, medium format was better than 135. At least that was the case in my experience, as long as I shot MF on tripod and didn't need very long depth of field and was shooting with low ISO film.. The Pentax 67 I had needed something like stopping down two extra stops to give the same DoF as my 135 camera. With tripod it was less a problem. What I essentially did was to use 67 with tripod and slow film for careful work and the 135 SLR for handheld shooting, using slow films in both.

Best regardsErik

In my experience, medium-format was always better regardless of how you shot or the ISO of the film. Granularity did not change with format and was effectively less the larger you went.

If photography is not a subjective medium, then you can make simple technical arguments. The problem is that results are purely subjective and so what is "better" is as diverse as the number of photographers. There are also economic factors. I think whatever technology is available, someone will find it ideal.

I don't think IQ will be the limiting factor in small sensors for most people in the future. We're at the point where people talk of shooting black cats in coal mines with sensors like the one found in a D3s; that's about 16x larger than the surface area of a Canon G12 giving it a 4-stop advantage. Supposing adding BSI (2 stops improvement) and Panasonic's grid (1-stop improvement or more according to the link posted in another thread) and another, yet to be invented improvement (1 more stop) to the sensor give us another 4-stop improvement over the D3s sensor and we scale it down. That would satisfy the needs of many people, even in dim indoor lighting.

What will be the limiting factor? Depth of field. Building lenses with tiny apertures will hit theoretical/practical limits and some people want shallow depth of field which would be unattainable at smaller sensor sizes (a lowly 50mm f/1.8 would need to be replaced by a 12mm f/0.11 on a G12). Barring something like this working with visible light and breaking the f/0.5 barrier, large sensors are here to stay.

For an open question like that you just forget about lens tech and sensor tech. Pretend both are perfect. How much light do you need to capture that type of scene with an acceptable S/N ratio? How much DR do you need? Any more is excess cost and excess weight.

With a larger format camera you would use a longer lens to achieve same FoV. For instance if you shoot 60 mm on APS-C a 90 mm lens would give the same field of view. Aperture would also be larger, as the diameter of the aperture is proportional to the focal length. So a 90 mm lens at f/8 would have an aperture diameter 12.5 mm while a 60 mm lens at f/8 would have 7.5 mm. So the area of the aperture would be 122.7 mm^2 vs 44.2 mm^2. Therefore the larger format/lens/aperture would collect more light.

On the other hand, the full frame 90 combo would need to be stopped down to f/12 to give the same DoF.

In my view, the smaller sensors make a lot of sense, provided lenses are purpose made for the small sensor size. This seems to be the case with 4/3 and Fuji X-mount but less so with other APS-C.

I've never understood this. We talk of "crop" sensors and if you take two images, one with a "crop" camera and the other with a "FF" camera and you then crop the FF image to give the same FoV as the crop image wont you get two images that look the same?

There will be differences as the chips will no doubt be slightly different but if we could get both FF and crop cameras with exactly the same chip technology I think they'd look the same. These days many of us have FF and crop cameras that can take the same lens and can try this little experiment and personally I have done it and the results look very largely the same to me. Near as makes no odds anyway. Yes the lenses work less hard on FF due to less magnification but keep image sizes reasonable and it may not matter.

Anyway, I digress... For me the smaller sensor cameras are good enough except when pushing ISO or print size to the absolute limits but I think that FF will live on.

My experience was that T-MAX 100 or Panatomic X on 135 would probably match TRI-X on 120. In my case I would normally use Panatomic-X, Velvia or T-MAX 100 on both 120 and 135 but I predominantly used 120 with Tripod/Mirror Lock Up and cable release.

In my experience, medium-format was always better regardless of how you shot or the ISO of the film. Granularity did not change with format and was effectively less the larger you went.

If photography is not a subjective medium, then you can make simple technical arguments. The problem is that results are purely subjective and so what is "better" is as diverse as the number of photographers. There are also economic factors. I think whatever technology is available, someone will find it ideal.

Ah, yes. I see what you mean. I was looking at using the same lens, settings and camera to subject distance and cropping

For me personally shooting with crop cameras and printing (if at all) to a max of A3, a crop is good enough in most instances but I can see how bigger will always be better when pushing the limits... unless you're also pushing the limits of what you can carry, deploy and use

When I went from 12 MP APS-C to 24 MP full frame I made a few comparisons and saw nut much of a difference. 24 MP full frame was better but I needed to see the images side by side. In one case I couldn't tell the images apart in print, although the image quality of the file was much better on the larger format. I normally print A2.

A year ago I shot a subject with both APS-C (16 MP) and full frame (24 MP). With APS-C I could use a better lens at a larger aperture and higher ISO. It was windy, and both DoF and wind were limitations. I ended up preferring the APS-C.

Nowdays I carry both FF and APS-C. Both are 24 MP, I use the APS-C for walk around and telephoto and the FF more for standard zoom on tripod shooting. Fo wide angles I use full frame.

I would suggest that smaller formats are good enough, but larger is still better if properly used.

Ah, yes. I see what you mean. I was looking at using the same lens, settings and camera to subject distance and cropping

For me personally shooting with crop cameras and printing (if at all) to a max of A3, a crop is good enough in most instances but I can see how bigger will always be better when pushing the limits... unless you're also pushing the limits of what you can carry, deploy and use

I just made a 3x4.5 foot print from a 12MP APS sensor. It was very nice. So much better than the 16x24 inch print.

But indeed, the truth today is that 99% of us (the super experts) don't need anything better than what a 645D/D800 can deliver in terms of sensor performance.

That means that these cameras cover 99.9999% of the needs of all photographers.

The best APS sensor found in the D5200 probably is good enough for 90% of experts needs, 99.999% of photographers, again in terms of sensor performance. It is equal or superior to film MF.

The rest is purely a matter of personal taste in terms of looks, DoF,...

As technology continues to progress, the ability of smaller sensors to cover the technical quality needs of photographers will increase. But the aesthetical preferences will also remain... That is until embedded software will have progressed enough to perfectly simulate larger formats rendering...

I know very little about NX. Regarding NEX the lenses are indeed made for the smaller format but few of the NEX lenses seem to be very good. Admittedly, I have only seen tests on the NEX.

Reducing the register is not as beneficial as it may be thought, as todays sensors don't work well with short back focus, anyway.

To compensate for the small image size the optics need to be better made. An APS-C sensor would need the same MTF at 60 lp/mm as a full frame sensor at 40 lp/mm. The better 4/3 lenses have decent MTF at 60 lp/mm, AFAIK.

It seems that most APS-C makers make one or two really good APS-C lenses and a few mediocre ones, leaving the upper end to full frame lenses.

Pentax makes only APS-C SLRs, but the MTF curves I have seen from their lenses don't really impress me, they are OK rather than excellent mostly.

Again, I might be wrong. My opinion is not formed on extensive testing of a lot of different equipment.

There are two sides to this question if bigger is better. On one hand larger IS technically better, or can be made better with the available technologies. What this means is bigger wins in test situations.

The other side is real life use. There smaller is often better as we are able to get the shots we are after with lighter equipment, but would often get nothing with bigger, heavier and clumsier cameras. Good quality picture is better than no picture, even if it would have been a great quality one... Just as an example: I have done a few documentary assignments lately with light APS-C size cameras (Fuji X-Pro1 & X-E1) even though I also have D4 and D800e with all the best lenses. APS-C kit weights 2.5 kg, the Nikon bag is 11.4 kg. With Fujis I can travel with hand luggage only and look like a harmless tourist (having only a tourist visa also), "professional" kit would make things vastly more complicated on many levels, which would mean less photos and less opportunities, even if the fewer shots would have slightly better IQ. There is also a practical limit of what is needed, good APS-C is as good as or better than midformat film used to be, and that is still good enough for a full spread in a glossy magazine. With 5 stops better ISO sensitivity also.

The point of my original posting was a bit that everything moves upscale. What you did with full format now perhaps you can do with APS-C or even 4/3. On the other hand, the larger formats also get better.

There are two sides to this question if bigger is better. On one hand larger IS technically better, or can be made better with the available technologies. What this means is bigger wins in test situations.

The other side is real life use. There smaller is often better as we are able to get the shots we are after with lighter equipment, but would often get nothing with bigger, heavier and clumsier cameras. Good quality picture is better than no picture, even if it would have been a great quality one... Just as an example: I have done a few documentary assignments lately with light APS-C size cameras (Fuji X-Pro1 & X-E1) even though I also have D4 and D800e with all the best lenses. APS-C kit weights 2.5 kg, the Nikon bag is 11.4 kg. With Fujis I can travel with hand luggage only and look like a harmless tourist (having only a tourist visa also), "professional" kit would make things vastly more complicated on many levels, which would mean less photos and less opportunities, even if the fewer shots would have slightly better IQ. There is also a practical limit of what is needed, good APS-C is as good as or better than midformat film used to be, and that is still good enough for a full spread in a glossy magazine. With 5 stops better ISO sensitivity also.

My sense and experience tell me that "all other factors being equal" (at leat theoretically) bigger will be better. At least until the level of resolution and dynamic range for a given sensor / display medium size exceeds human vision. Once that limit it reached then one could speculate "at what sensor size" has it been reached. Improvements from that point forward could drive sensor size downward.

None of my speculation takes into account the other differences in image characteristics that derive from relative sensor size, however.